Answer:
m = 3.75 [kg]
Explanation:
We must remember that momentum is defined as the product of mass by Velocity, therefore it can be represented by means of the following equation.

where:
P = momentum = 93.75 [kg*m/s]
m = mass [kg]
v = velocity = 25 [m/s]
Now replacing, we can clear the mass:
![P=m*v\\m=P/v\\m=93.75/25\\m=3.75 [kg]](https://tex.z-dn.net/?f=P%3Dm%2Av%5C%5Cm%3DP%2Fv%5C%5Cm%3D93.75%2F25%5C%5Cm%3D3.75%20%5Bkg%5D)
Answer:
(a) the runner's kinetic energy at the given instant is 308 J
(b) the kinetic energy increased by a factor of 4.
Explanation:
Given;
mass of the runner, m = 64.1 kg
speed of the runner, u = 3.10 m/s
(a) the kinetic energy of the runner at this instant is calculated as;

(b) when the runner doubles his speed, his final kinetic energy is calculated as;

the change in the kinetic energy is calculated as;

Thus, the kinetic energy increased by a factor of 4.
<span>Nonliving things also have unlimited duration of existence. While living things die and decompose, nonliving things such as rocks, mountains, air and water have existed for millions of years. They may grow, but they do so only by accretion, which is the process of growth by accumulating added layers of matter.</span>
At the point where the ball stops it has speed of 0 m/s. When it continues to fall in every meter it gets 9.8 m/s so you just put this :
9.8 m/s2 x 2.5 m = 24.5 m/s